Cantilever shelf assembly with pantography support arrangement for refrigerators

ABSTRACT

A refrigerator shelf assembly for moving a plurality of cantilevered vertically stacked adjustable shelves to a staggered extended position by a pair of composite stringer linkage mechanisms each pivotally supported in spaced relation to the refrigerator and movable in parallel vertical planes in a pantograph manner while maintaining the shelves in horizontally disposed relation, together with actuator means for automatically moving the shelves.

United States Patent [191 Jacobs [5 1 CAN'llLEVER SHELF ASSEMBLY WITHPANTOGRAPHY SUPPORT ARRANGEMENT FOR REFRIGERATORS [75] Inventor: JamesW. Jacobs, Dayton, Ohio [73] Assignee: General Motors Corporation,Detroit, Mich.

[111 3,814,492 1 June 4, 1974 2,654,345 10/1953 Edwards 312/2712,795,691 6/1957 Solley et a1. 312/223 X 2,956,766 10/1960 Galassi248/243 3,139,258 6/1964 Handler et al....... 248/243 3,177,988 4/1965Costantini et al.... 248/243 X 3,231,732 1/1966 Ferguson 312/223 X3,578,833 5/1971 Frederick 312/273 3,712,521 1/1973 Tanner 211/150 XPrimary Examiner-Paul R. Gilliam Attorney, Agent, or Firm-Edward P.Barthel [57] ABSTRACT A refrigerator shelf assembly for moving aplurality of cantileveredvertically stacked adjustable shelves to astaggered extended position by a pair of composite stringer linkagemechanisms each pivotally supported in spaced relation to therefrigerator and movable in parallel vertical planes in a pantographmanner while maintaining the shelves in horizontally disposed relation,together with actuator means for automatically moving the shelves.

5 Claims, 9 Drawing Figures CANTILEVER SHELF ASSEMBLY WITH PANTOGRAPHYSUPPORT ARRANGEMENT FOR REFRIGERATORS This invention relates torefrigerator cabinet shelves and more particularly to a refrigeratorshelf mechanism for moving a plurality of cantilevered adjustableshelves to a staggered extended position while maintaining the shelvesin horizontally disposed relation.

It is therefore an object of this invention to provide a pair ofpantograph linkage mechanisms in combination with a plurality ofcantilevered supported adjustable shelves for a cabinet structurewhereby the shelves are movable in unison to an outer staggered positionwhile being maintained in a horizontal attitude.

It is another object of the invention to provide a shelf assembly for arefrigerator cabinet including a plurality of cantilevered verticallystacked adjustable shelves, each supported by rearwardly extending upperand lower hook-like projections, for movement of the shelves in unisonto a staggered extended position on a pair of composite aperturedstringers wherein each composite stringer comprises a pair ofcoextensive channels dimensioned to be nested in opposed box-likesections such that each channel is pivotally attached to the cabinet atits upper end while the free ends of the channels are pivotally linkedtogether providing a pair of linkage mechanisms movable inspaced-parallel vertical planes in a pantograph manner. The upper andlower projections of each shelf have cammed forwardly and rearwardlyfacing arcuate edges respectively operatively engaging its associatedcomposite stringer maintaining the horizontal position of the shelveswhile the assembly is moved either manually or by power assist means toan extended or retracted position.

Other objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred embodiment of the present invention isclearly shown.

In the Drawings:

FIG. 1 is a perspective view of a refrigerator cabinet with the doorshown in open position and the shelf assembly extended;

FIG. 2 is a vertical side view partly in section and partly in elevationof the cabinet of FIG. 1 with the shelf assembly shown in full lines inretracted position;

FIG. 3 is an enlarged fragmentary detail view partly in section of therear mounting tabs and upper pivotal support, partly in section with theshelf assembly shown in retracted position;

FIG. 4 is an enlarged fragmentary detail view of the rear mounting tabsand lower pivotal link partly in section with shelf assembly shown inextended position;

FIG. 5 is a horizontal section taken on the line S-.5 of FIG. 3;

FIG. 6 is an enlarged fragmentary detail view partly in section of theshelf assembly linear motor actuator;

FIG. 7 is an enlarged section taken on the line 7-7 of FIG. 6; v

FIG. 8 is a schematic wiring diagram for power extending the shelfassembly;

FIG. 9 is an optional schematic wiring diagram for power extending andreturning the shelf assembly.

Referring to the drawings, for illustrating my invention. I show inFIGS. 1 and 2 thereof a generally rectangular cabinet 10 of a householdrefrigerator or freezer. The refrigerator cabinet 10 includes an outersheet metal shell 11 and an inner box-like plastic liner I2 spaced fromthe shell and having any suitable or desirable insulating material l3disposed therebetween. as seen in FIG. 3. Liner 12 forms rectangularwalls of a polygonal-shaped food storage chamber 14 between top wall 15and lower storage bins 16 within cabinet 10 which is practical formaximum food storage space, and wherein my invention is particularlyapplicable. Food storage chamber 14 is provided with an open frontaccess opening 17 which is normally closed by an insulated doorstructure generally represented by the reference character 18 hingedlysecured to one vertical edge of the cabinet 10 by suitable hinges 20 forhorizontal swinging movement relative thereto.

As best seen in FIGS. 3, 4 and 5, the liner includes a rear wall 21having horizontally spaced pivotal means for supporting two compositestringers 22, 23. Each composite stringer or linkage mechanism has itsupper end received by respective U-shaped brackets 24 and 25 which aresuitably secured by their base flanges to the rear wall 21 of the lineradjacent the juncture with top wall 15 such as by screws 26. As each ofthe composite stringers are identical, common reference numerals will beused to designate corresponding portions thereof.

Each of the composite stringers 22, 23 comprise apair of elongatedcoextensive front and rear channel members 31 and 32 respectivelydimensioned such that smaller sectioned front channel member 31 isnestably received within larger sectioned rear channel member 32. Thefront channel member 31 has a pair of upstanding ears 35 and 36 havingaligned apertures therethrough to receive a first transverse pin 38therethrough which has its outer extremities pivotally supported inaligned apertures in the side flanges 39 and 40 of the U-shaped bracketsto allow for relative pivotal movement between the inner front channelmember 31 and the rear outer channel member 32. In a similar manner therear channel member 32 has a pair of upwardly extending ear portions 42and 43 having aligned apertures therein for reception of a secondtransverse pin 44, the extremities of which are pivotally supported inthe side flanges 39 and 40 of its associated U-shaped bracket 24, toallow the rear channel member 32 to pivot relative to the front channelmember 31. It will be noted in FIG. 3 that the pivotal axis of each ofthe first and second pins 38 and 44 are aligned in spaced parallelrelation in a common horizontal plane. The front inner channel member 31has a plurality of equally spaced apertures 50 in its transverse wallsuch that the apertures 50 form cross webs 52 therebetween.

A plurality of article supporting cantilevered shelves or trays arelocated in the cabinet 14 which in the disclosed embodiment comprisethree identical trays indicated generally at 61, 62 and 63. As bestshown in FIGS. 1 and 3, each shelf includes a pair of opposite sidebrackets or beams 66 and 67 such that each pair of side members define ashelf unit and support a top plate 68 which is suitably secured to theupper edge of the side beams 66 and 67 such as by welding. The rearportion of each side bracket includes upper and lower hook-likeprojections 71 and 72 and a bottom tab 73 such that the upper projection71 is received in one aperture 50aof the front channel member 31 withthe downwardly extending hook engaging behind the associated web 52 ofthe channel below the aperture 50a while the bottom tab 73 is receivedin an aperture designated 50c.'The forward edge of upper projection 71is outwardly curved to provide a first arcuate camming edge 74 designedto contact and ride against its associated web 52 while the rear edge 75is spaced from the transverse wall 77 of rear channel 32 at all times.The lower projection 72 is received in the aperture 501) such that itsdownwardly extending hookhas its rearward edge portion outwardly curvedto provide a second arcuate camming edge 76 dimensioned to engage andride against the transverse wall 77 of the rear channel 32. The arcutecam 76 allows the projection 72 to compensate for the reduction inspacing from a greater normal distance X (FIG. 3) to a lesser normaldistance Y (FIG. 4) between the respective transverse wall 77 and thewebs 52 of the rear and front channels as they are pivoted outwardly.

The lower extremities of each of the front and rear nested channels 31,32 are similarly each provided with a pair of ears 81, 82 which extenddownwardly with each pair having aligned apertures therein to receivefirst and second transverse pivot pins 83, 84 therethrough for pivotalengagement with pairs of link members 88. The pins 83 and 84 are locatedin a horizontal plane and are spaced a distance equal to the spacebetween the upper pins 38 and '44'such that each of composite stringers22, 23 functions as a pantograph member whereby when it is pivotedoutwardly from the rear wall 25'the lower links 88 and upper bracketsare so connectedand proportioned as to length in the form of aparallelogram that any motion of one point in a plane parallel to thatof each composite stringer mechanism will cause another point to followa similar path.

In this manner when the shelves 61, 62 and 63 are supported on thecomposite stringers22, 23 in the horizontal attitudes and in verticallystacked spaced apart relation they, are arranged to be moved in unisonthrough the open front access opening 17 to the broken line positionshown in FIG. 2.

1 Positioned in the lower portion of the refrigerator cabinet is alinear induction motor 90 which is preferably of the flat type, i.e., itis essentially a squirrel cage motor split along the armature axis andunrolled into a flat plane. One example of a flat linear induction motoris disclosed in US. Pat. No. 3,335,300 issued-Aug. 8, 1967 to VonBrimer, and reference should be had to this patent for details of itsoperation.

The movable element or armature 92 of the linear induction motoractuator 90 preferably is shaped with an l-cross section as seen in FIG.7 of the drawings. Armature 92, formed of a conductive material, isslidably mounted between a magnetic keeper element 94 and the primary orstator 96 having windings 98 which may be selectively energized tocorrespondingly move the armature up or down bycircuit means to bedescribed. The linear motor 90 is enclosed in a housing 100 havingflanges 102 for suitably affixing the motor to the rear wall 21 of thecabinet by fasteners 104. Outer nylon bearing surfaces indicated at 106and inner nylon bearing surfaces 108 are provided to guide the verticaltravel of the armature.

The upper end of the armature 92 has suitable stop means thereon in theform of a stop connector 110 operably mounted on one end of a controlwire 112 which has a loop 114 on the other end thereof operably attachedto a connector pin 116 located on the side member 67 of the lowermostshelf so that vertical upward movement of the armature 92 produces acorresponding movement of the shelf assembly to move the shelves totheir outer-extended position. Surrounding the wire 112 is a flexiblesheath 120 which is conventionally anchored at each end to the wiresupport 122 which is screwed to the rear wall of the cabinet at 124.Push-pull control wire systems, also known as Bowden controllers," aredisclosed, for example, in US. Pat. No. 3,546,962 issued Dec. 15, 1970to Ruhala and assigned to the assignee of the instantapplication. andreference may be had to the Ruhala patent for details of a typicalcontrol wire structure. In FIG. 6 the actuator means is shown in itsshelf assembly retracted position wherein the stop member is bottomed onthe upper surface of the linear motor housing 100. While the disclosedform shows one actuator means 90 driving the left hand linkage mechanism22 only, itis within the scope of the invention that a second actuatormeans could be employed to simultaneously drive the right hand linkagemechanism 23.- I

With reference to F IG. 1, a door switch is shown on the lower mullionof the cabinet which is actuated by disengagement with the door 18 ofthe refrigerator and is serviced through a circuit shown in FIG. 8 toclose the switch 130 to fixed contact 131- energizing the circuit L, toline L through conductors 132 and 133 to ashelfposition control switch136 located at a convenient height on the vertical mullion strip 138 ofthe cabinet which is shown as a single pole-single throw normallyopenswitch having its movable contact 140 in open position engagingfixed open contact 141. ln"

operation and with the door opened the user can-close the shelf positioncontrol switch 136 by moving the movable contact 140 into engagementwith fixed contact 142 energizing the coils 98 .to the line L through aphase shifting capacitor 144 whereby the linear motor actuator 92 movesupwardly transmitting up-' ward motion to the wire 112 which in turnpivots the shelf assembly to. its outward phantom line position of FIG.2. The shelf assembly is held in this position as long as switches 130and 136 are closed. In this form of the invention the'shelf assembly isreturned to its normally retracted position by means of gravity or by asmall force imparted by the operator.

A modified circuit arrangement is shown in FIG. 9 with similar elementshaving the same reference numerals whereby a single pole-double throwswitch is utilized with the actuator 90 such that with the door 18opened to close switch 130 to contact 131, and with the movable contact151 positioned to fixed contact 152, the actuator 90 moves the shelfassembly to its outer extended position. in this arrangement when themovable contact 151 is subsequently moved to engage fixed contact 153 acircuit is completed to the other side of the line L causing thearmature to move downward and power return the shelves to theirretracted position. Therefore it is apparentthat depending upon theposition of movable contact 151, the shelves can be caused toautomatically extend whenever door 18 is opened sufficiently to closeswitch 130 against contact 131 and movable contact .151 is positioned tofixed contactl52. On the other hand, if the movable contact 151 ispositioned against fixed contact 153, the shelves will remain within thecabinet, even though switch 130 is closed against contact 13].Obviously, whenever the door is moved sufficiently toward its closedposition to move switch 130- away from contact 131 the actuator isdeactivated and the shelf assembly may return by gravity or by a manualassist to its inner position.

While the embodiment of the present invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted.

I claim:

1. In a cabinet comprising wall structure defining a box-like storagecompartment provided with a front access opening and a door for saidopening, said wall structure including a rear wall and opposite sidewalls, a shelf assembly including a plurality of cantileveredhorizontally disposed shelves supported in said compartment one abovethe other by means of a plurality of spaced apart pantograph-typecomposite stringer linkages, a bracket for pivotally supporting eachsaid stringer linkage solely from said rear wall of said compartment fortravel in a common vertical plane resulting in combined upward andoutward movement of said shelf assembly from an inner retracted positionto an outer extended position, each said composite stringer linkagebeing vertically oriented in said cabinet when said shelf assembly is inits retracted position, each said composite stringer linkage including apair of outer and inner coextensive elongated structural elements, saidouter structural element having a transverse wall provided withvertically spaced openings therein, each of the shelves having aplurality of spacedcantilever support arms, each said support arm rearportion including upper and lower hook-like projections arranged to bedirected into respective ones of said spaced openings in its associatedouter structural element whereby it is supported in cantilevered fashiontherefrom, said upper projection having its forward edge outwardlycurved to provide a first arcuate camming edge wedgingly contacting theinner face of said outer structural element transverse wall, said lowerprojection having its rearward edge outwardly curved to provide a secondarcuate camming edge wedgingly contacting the inner face of said innerstructural element transverse wall, each said structural element pivotedat its upper end to its associated bracket, link means pivotallyconnecting the lower ends of each pair of said structural elements, thepivots of said bracket and the link means of each pair of structuralelements being positioned to lie in the four corners of a parallelogramlinkage whereby said shelf assembly may be angularly moved from saidretracted position to an outer extended position, said support armsfirst and second arcuate camming edges being shaped to maintain opposedsliding wedged contact with their associated channel faces whereby saidshelves are moved into stepped relation in their extended position withno substantial tilting from the horizontal.

2. The combination of claim 1 including electric motor driven stringerlinkage actuating means connected to at least one of said linkages forangularly moving said one linkage whereby said shelf assembly will bemoved from its retracted position to an extended position.

3. ln a refrigerator cabinet comprising wall structure defining abox-like storage compartment provided with a front access opening and adoor for said opening, said wall structure including a rear wall andopposite side walls, a shelf assembly including a plurality ofhorizontally disposed cantilevered shelves supported in said compartmentin vertically stacked relation therein by means of first and secondspaced apart pantographtype composite stringer linkages, a bracket forpivotally supporting each said stringer linkage solely from said rearwall of said compartment for travel in a common vertical plane resultingin combined upward and outward movement of said shelf assembly from aninner retracted position to an outer extended position, each said firstand second composite stringer linkage being vertically oriented in saidcabinet at a corner juncture defined by said rear wall and its adjacentside wall when said shelf assembly is in its retracted position, eachsaid composite stringer linkage including a pair of outer and innercoextensive channels dimensioned to nest in opposed relation to form abox-shaped section, said outer channel having its transverse wallprovided with vertically spaced openings therein, each of the shelveshaving a pair of spaced cantilever support arms, each said support armrear portion including upper and lower hook-like projections arranged tobe directed into respective ones of said spaced openings in itsassociated outer channel whereby it is supported in cantilevered fashiontherefrom, said upper projection having its forward edge outwardlycurved to provide a first arcuate camming edge wedingly contacting theinner face of said outer channel transverse wall, said lower projectionhaving its rearward edge outwardly curved to provide a second arcuatecamming edge wedgingly contacting the inner face of said inner channeltransverse wall, each said channel pivoted at its upper end to itsassociated bracket means, link means pivotally connecting the lower endsof said nested channels, the pivots of said bracket and said link meansof each being positioned to lie in the four corners of a parallelogramlinkage whereby upon said shelf assembly being angularly moved from saidretracted position to an outer extended position, said support armsfirst and second arcuate camming edges being shaped to maintain opposedsliding wedged contact with their associated faces whereby said shelvesare moved into stepped relation with no substantial tilting from thehorizontal.

4. In a cabinet comprising wall structure defining a box-like storagecompartment provided with a front access opening and a door for saidopening, said wall structure including a rear wall and opposite sidewalls, a shelf assembly including a cantilevered horizontally disposedshelf supported in said compartment by means of a plurality of spacedapart pantograph-type composite stringer linkages, a U-shaped bracketfor pivotally supporting each said stringer linkage solely from saidrear wall of said compartment for travel in a common vertical planeresulting in combined upward and outward movement of said shelf assemblyfrom an inner retracted position to an outer extended position, eachsaid composite stringer linkage being vertically oriented in saidcabinet when said shelf assembly is in its retracted position, each saidcomposite stringer linkage including a pair of outer and innercoextensive elongated structural elements, said outer structural elementhaving a transverse wall provided with vertically spaced openingstherein, said shelf having a plurality of spaced cantilever supportarms, each said support arm rear portion including upper and lowerhook-like projections arranged to be directed into respective ones ofsaid spaced openings in its associated outer structural 7 elementwhereby it is supported in cantilever fashion therefrom, said upperprojection having its forward edge outwardly curved to provide a firstarcuate camming edge wedgingly contacting the inner face of said outerstructural element transverse wall, said lower projection having itsrearward edge outwardly curved to provide a second arcuate camming edgewedgingly contacting the inner face of said inner structural elementtransverse wall, each said structural element pivoted at its upper endto its associated bracket, link means pivotally connecting the lowerends of each pair of said structural elements, the pivots of the bracketmeans and the link means of each pair of structural elements beingpositioned to lie in the four corners of a parallelogram linkage wherebysaid shelf assembly being angularly movable from said retracted positionto an outer extended position, said support arms first and motor to movesaid shelf assembly from its retracted position to an outer extendedposition.

5. The combination of claim 4 including shelf position control switchmeans for selectively energizing the windings of said linear electricmotor whereby said motor may be reversed to move said shelf assemblyeither to an extended or retracted position upon the opening of saiddoor.

1. In a cabinet comprising wall structure defining a box-like storagecompartment provided with a front access opening and a door for saidopening, said wall structure including a rear wall and opposite sidewalls, a shelf assembly including a plurality of cantileveredhorizontally disposed shelves supported in said compartment one abovethe other by means of a plurality of spaced apart pantograph-typecomposite stringer linkages, a bracket for pivotally supporting eachsaid stringer Linkage solely from said rear wall of said compartment fortravel in a common vertical plane resulting in combined upward andoutward movement of said shelf assembly from an inner retracted positionto an outer extended position, each said composite stringer linkagebeing vertically oriented in said cabinet when said shelf assembly is inits retracted position, each said composite stringer linkage including apair of outer and inner coextensive elongated structural elements, saidouter structural element having a transverse wall provided withvertically spaced openings therein, each of the shelves having aplurality of spaced cantilever support arms, each said support arm rearportion including upper and lower hook-like projections arranged to bedirected into respective ones of said spaced openings in its associatedouter structural element whereby it is supported in cantilevered fashiontherefrom, said upper projection having its forward edge outwardlycurved to provide a first arcuate camming edge wedgingly contacting theinner face of said outer structural element transverse wall, said lowerprojection having its rearward edge outwardly curved to provide a secondarcuate camming edge wedgingly contacting the inner face of said innerstructural element transverse wall, each said structural element pivotedat its upper end to its associated bracket, link means pivotallyconnecting the lower ends of each pair of said structural elements, thepivots of said bracket and the link means of each pair of structuralelements being positioned to lie in the four corners of a parallelogramlinkage whereby said shelf assembly may be angularly moved from saidretracted position to an outer extended position, said support armsfirst and second arcuate camming edges being shaped to maintain opposedsliding wedged contact with their associated channel faces whereby saidshelves are moved into stepped relation in their extended position withno substantial tilting from the horizontal.
 2. The combination of claim1 including electric motor driven stringer linkage actuating meansconnected to at least one of said linkages for angularly moving said onelinkage whereby said shelf assembly will be moved from its retractedposition to an extended position.
 3. In a refrigerator cabinetcomprising wall structure defining a box-like storage compartmentprovided with a front access opening and a door for said opening, saidwall structure including a rear wall and opposite side walls, a shelfassembly including a plurality of horizontally disposed cantileveredshelves supported in said compartment in vertically stacked relationtherein by means of first and second spaced apart pantograph-typecomposite stringer linkages, a bracket for pivotally supporting eachsaid stringer linkage solely from said rear wall of said compartment fortravel in a common vertical plane resulting in combined upward andoutward movement of said shelf assembly from an inner retracted positionto an outer extended position, each said first and second compositestringer linkage being vertically oriented in said cabinet at a cornerjuncture defined by said rear wall and its adjacent side wall when saidshelf assembly is in its retracted position, each said compositestringer linkage including a pair of outer and inner coextensivechannels dimensioned to nest in opposed relation to form a box-shapedsection, said outer channel having its transverse wall provided withvertically spaced openings therein, each of the shelves having a pair ofspaced cantilever support arms, each said support arm rear portionincluding upper and lower hook-like projections arranged to be directedinto respective ones of said spaced openings in its associated outerchannel whereby it is supported in cantilevered fashion therefrom, saidupper projection having its forward edge outwardly curved to provide afirst arcuate camming edge wedingly contacting the inner face of saidouter channel transverse wall, said lower projection having its rearwardedge Outwardly curved to provide a second arcuate camming edge wedginglycontacting the inner face of said inner channel transverse wall, eachsaid channel pivoted at its upper end to its associated bracket means,link means pivotally connecting the lower ends of said nested channels,the pivots of said bracket and said link means of each being positionedto lie in the four corners of a parallelogram linkage whereby upon saidshelf assembly being angularly moved from said retracted position to anouter extended position, said support arms first and second arcuatecamming edges being shaped to maintain opposed sliding wedged contactwith their associated faces whereby said shelves are moved into steppedrelation with no substantial tilting from the horizontal.
 4. In acabinet comprising wall structure defining a box-like storagecompartment provided with a front access opening and a door for saidopening, said wall structure including a rear wall and opposite sidewalls, a shelf assembly including a cantilevered horizontally disposedshelf supported in said compartment by means of a plurality of spacedapart pantograph-type composite stringer linkages, a U-shaped bracketfor pivotally supporting each said stringer linkage solely from saidrear wall of said compartment for travel in a common vertical planeresulting in combined upward and outward movement of said shelf assemblyfrom an inner retracted position to an outer extended position, eachsaid composite stringer linkage being vertically oriented in saidcabinet when said shelf assembly is in its retracted position, each saidcomposite stringer linkage including a pair of outer and innercoextensive elongated structural elements, said outer structural elementhaving a transverse wall provided with vertically spaced openingstherein, said shelf having a plurality of spaced cantilever supportarms, each said support arm rear portion including upper and lowerhook-like projections arranged to be directed into respective ones ofsaid spaced openings in its associated outer structural element wherebyit is supported in cantilever fashion therefrom, said upper projectionhaving its forward edge outwardly curved to provide a first arcuatecamming edge wedgingly contacting the inner face of said outerstructural element transverse wall, said lower projection having itsrearward edge outwardly curved to provide a second arcuate camming edgewedgingly contacting the inner face of said inner structural elementtransverse wall, each said structural element pivoted at its upper endto its associated bracket, link means pivotally connecting the lowerends of each pair of said structural elements, the pivots of the bracketmeans and the link means of each pair of structural elements beingpositioned to lie in the four corners of a parallelogram linkage wherebysaid shelf assembly being angularly movable from said retracted positionto an outer extended position, said support arms first and secondarcuate camming edges being shaped to maintain opposed sliding wedgedcontact with their associated faces whereby said shelf is moved with nosubstantial tilting from the horizontal, a linear electric motor withinsaid compartment, flexible control wire means operatively connected toone of said support arms controlled by said motor, door switch meanscontrolled by the opening of said door to energize said motor to movesaid shelf assembly from its retracted position to an outer extendedposition.
 5. The combination of claim 4 including shelf position controlswitch means for selectively energizing the windings of said linearelectric motor whereby said motor may be reversed to move said shelfassembly either to an extended or retracted position upon the opening ofsaid door.